Description

The GE UR-8NH (officially designated 336A5975P1) is an 8-channel high-level digital output (DO) module designed for the GE Mark VIe distributed control system—GE’s flagship platform for turbine control in power generation, oil & gas, and industrial energy applications. Unlike low-level transistor outputs, the UR-8NH features electromechanical relays on each channel, enabling it to directly switch AC or DC loads up to 250 V / 2 A, making it ideal for driving solenoids, alarm horns, motor starters, trip relays, and other field devices without external interposing relays.

Each output is a Form C (SPDT) relay contact (Normally Open + Normally Closed + Common), providing maximum wiring flexibility. The module is installed in a Mark VIe I/O Pack (typically in a rugged IP66-rated enclosure near the turbine) and communicates with the central VCMI or VPRO controller via GE’s deterministic I/ONET protocol over dual Gigabit Ethernet. The UR-8NH supports hot-swap replacement and automatic configuration recovery—critical for minimizing downtime during maintenance in continuous-operation plants.

Designed for safety-critical functions, the UR-8NH includes opto-isolation between logic and field sides, along with surge suppression on all outputs, ensuring resilience against voltage spikes from inductive loads (e.g., valve coils). Its robust construction meets the demanding environmental standards of combined-cycle and peaking power plants, where temperature swings, vibration, and EMI are constant challenges.

⚙️ Technical Specifications

✅ Main Features and Advantages

Direct Field Device Control Without Interposing Relays:
The UR-8NH eliminates the need for external relay panels by providing line-voltage switching capability directly from the I/O module. This reduces panel space, wiring complexity, and points of failure—especially valuable in retrofit projects or compact skid-mounted turbines.

High Reliability for Safety Functions:
Electromechanical relays offer true galvanic separation and fail-safe behavior (contacts open on coil de-energization). In turbine trip sequences, this ensures that critical valves or breakers respond even if the control system loses power—aligning with SIL requirements in many protection schemes.

Seamless Integration with Mark VIe Diagnostics:
Each relay’s status (energized/de-energized) is monitored and reported to the Mark VIe ToolboxST software. Technicians can remotely verify output states, detect welded contacts, or simulate commands—accelerating troubleshooting during outages.

Robust Industrial Design:
Conduction-cooled (no fans), conformal-coated PCBs, and metal shielding make the UR-8NH resistant to dust, moisture, and electrical noise—ensuring decades of service in harsh power plant environments.

? Application Field

• Gas & Steam Turbine Trip Systems: Driving emergency shutdown solenoids on fuel valves

• Generator Protection: Tripping field breakers or synchronizing relays

• Auxiliary Systems: Controlling lube oil pumps, cooling fans, or space heaters

• Alarm & Annunciator Panels: Activating visual/audible alarms for high vibration or high exhaust temp

• Combined-Cycle Plants: Coordinating HRSG damper actuators or water injection valves

? Related Products

• UR-4D: 16-channel digital input module (companion to UR-8NH)

• 029.381539/00: 16-channel analog input module

• 029.381540/00: Analog output module

• Mark VIe I/O Pack (e.g., 029.381500 series): Enclosure housing UR-8NH

• VCMI / VPRO Controllers: Central Mark VIe processing units

• ToolboxST Software: For configuration, diagnostics, and firmware updates